Gas-blast circuit interrupters with both stationary and movable pneumatically-operated contacts



1965 J. E. SCHRAMECK ETAL 3,214,548

GAS-BLAST CIRCUIT INTERRUPTERS WITH BOTH STATIONARY AND MOVABLEPNEUMATICALLY-OPERATED CONTACTS Filed Jan. 24, 1962 5 Sheets-Sheet 1V////////[&

. INVENTORS WITNESSES. Jack E Schromeck 0nd Rm/W81 R 6 WigiYom R. Segor.

Oct. 26, 1965 J. E. SCHRAMECK ET 3,214,548 GAS-BLAST CIRCUITINTERRUPTERS WITH TATIONARY AND MOVABLE PNEUMATICALLY-OPERATED TS FiledJan. 24, 1962 Sheets-Sheet 2 26 32 Fig.3. 2s

1965 J. E. SCHRAMECK ETAL 3,214,548

GAS-BLAST CIRCUIT INTERRUPTERS WITH BOTH STATIONARY AND MOVABLEPNEUMATICALLY-OPERATED CONTACTS Filed Jan. .24, 1962 5 Sheets-Sheet 3United States Patent 3,214,548 GAS-BLAST CIRCUIT INTERRUPTERS WITH BOTHSTATIONARY AND MOVABLE PNEUMATICAL- LY-OPERATED CONTACTS Jack E.Schrameck, Pittsburgh, and William R. Segar, Breutwood Boro, Pa.,assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Filed Jan. 24, 1962, Ser. No. 168,396 8Claims. (Cl. 200-148) This invention relates generally to compressed-gascircuit interrupters and, more particularly to compressed-gas circuitinterrupters having contacts which are pneumatically actuated.

A general object of the present invention is to provide an improvedcompressed-gas circuit interrupter which is of high speed and in whichare erosion of the contacts is considerably reduced.

A more specific object of the present invention is to provide animproved compressed-gas circuit interrupter in which pressure-responsivemeans is associated with the relatively stationary contact structure ofthe circuit interrupter to insure that the main relatively stationarycontacts will have no arc-erosive action exerted thereon.

Another object of the present invention is the provision of an improvedcompressed-gas circuit interrupter in which the main contacts areseparated more rapidly than the arcing contacts of compressed-gascircuit interrupters of the prior art; and, consequently, the overlapdistance between the arcing contacts maythereby be shortened to resultin a circuit interrupter of considerably reduced arcing time.

Still another object of the present invention is the provision of animproved compressed-gas circuit interrupter in which by the simpleexpedient of utilizing the gas blast, which is normally used to effectare interruption, the relatively stationary contact structure may bemodified to provide faster breaker operation, and, in addition, toreduce arc erosion exerted upon the contacts.

Generally, according to one particular feature of the present invention,an extendable auxiliary arcing contact is piston-actuated to eliminatearcing at the relatively stationary contacts. The gas blast, which isemployed during the opening operation, is effective to operate thepiston-actuated auxiliary contact toward the opening direction of themovable contact, so that the arc will be established between the movableand auxiliary contacts and not at the relatively stationary contact. Asa result, the contact surfaces of the relatively stationary contact aremaintained free of pitting and other arc-erosive action, was to be ingood current-carrying condition in the closed-circuit position of theinterrupter. According to another feature of the present invention, maincontact structure is associated with arcing contact structure, andpressure-responsive means, responsive to the blast pressure, is operableto effect movement of the main movable contact structure in oppositedirections to thereby more quickly effect the separation thereof. Theoverlap distance between the arcing contact structure may, therefore, beminimized to consequently result in a breaker having a shorter arcingperiod.

Further objects and advantages will readily become apparent upon readingthe following specification taken in conjunction with the drawings, inwhich:

FIG. 1 illustrates a side elevational view of a compressed-gas circuitinterrupter embodying features of the present invention, the contactstructure being illustrated in the closed-circuit position;

FIG. 2 is a considerably enlarged fragmentary view of the contactstructure disposed at the upper end of the circuit interrupter of FIG.1, the contact structure likewise being illustrated in theclosed-circuit position;

ice 1 FIG. 3 is a fragmentary view, somewhat similar to that of FIG. 2,but illustrating the position of the several contact parts during theexistence of blast pressure conditions, with the auxiliary contact beingshown in its extended position;

FIG. 4 illustrates a modification of the invention taken substantiallyalong the line IV-IV of FIG. 5, the contact structure being illustratedin the closed-circuit position;

FIG. 5 is a sectional view taken substantially along the line V-V ofFIG. 4, again the contact structure being illustrated in theclosed-circuit position; and

FIG. 6 is a fragmentary view somewhat similar to that of FIG. 5, butillustrating the position of the several parts during the initialportion of the opening operation under blast-pressure conditions, inwhich the piston-actuated movable main contacts are illustrated in theirpartially retracted position.

Referring to the drawings and more particularly to FIG. 1 thereof, thereference numeral 1 generally designates a compressed-gas circuitinterrupter. Generally, the compressed-gas circuit interrupter 1includes a tank of high-pressure gas 2 containing a suitablehigh-pressure fluid 3, such as air under pressure. The pressure mayapproximate 300 p.s.i.g., for example.

Blast valve means, generally designated by the reference numeral 4, iseffective to control the passage of high-pressure gas 3 from the tank 2upwardly through a blast tube 5 and into an arc-chute structure 6,within which the established arc is extinguished, as more fully broughtout hereinafter. Reference may be had to United States Patent 2,739,206issued March 20, 1956, to Fritz E. Florschutz and Raymond H. Leitzel,and assigned to the assignee of the instant application for adescription of the operation of the blast-valve mechanism 4. Briefly,the operation of the blast-valve structure 4 is such thatcounterclockwise rotation of the operating shaft 7, as effected by apiston rod 8, causes a cam 10 to valve disposed within the valve casing12, and permit thereby a blast of gas to pass upwardly through the blasttube 5 between a movable hook-shaped and blade-shaped contact 13 andrelatively stationary contact structure, generally designated by thereference numeral 14. As well known by those skilled in the art, theare, which is established between the contact structure 13, 14, is movedlaterally upwardly into the arc-chute structure 6, where suitablesplitter plates or other interrupting structure may be disposed toeffect rapid extinction of the established arc.

FIG. 2 shows somewhat fragmentarily, and on a considerably enlargedscale the relatively separable con tact structures 13, 14 associatedwith the circuit interrupter 1. With reference to FIG. 2, it will benoted that the movable hook-shaped and blade-shaped contact 13 iscooperable with a jaw-type flexible relatively stationary contact 14comprising a pair of split furcations 14a, between which the tip portion13a of the movable contact enters for good contacting engagement, asillustrated by the closed-circuit position of FIG. 2. Additionally, itwill be observed that an auxiliary movable arcing contact 16, having anarc-resisting tip portion 16a, is associated with the upper tip portion13b of the movable contact 13. The movable auxiliary arcing contact 16is fixedly secured to an operating rod 17 having a rod-end 18 securedthereto. Pivotally connected, as at 20, to the rod-end 18 is a rotatableactuating lever 21, pivotally supported intermediate its ends upon astationary pivot 22, and having the lower end thereof linked, as at 23,to a link 24. The left-hand end of the link 24, as viewed in FIG. 2, ispivotally connected, as at 25, to a pressure-responsive means 26,assuming the form of a piston 27, which is responsive to the blastpressure present within a conduit 28, leading to the interior of theblast tube 5, as at the location 30.

From the foregoing description, it will be obvious that during theexistence of blast pressure conditions within the interior 31 of theblast tube 5, this blast pressure will act through the conduit 28 andefiect rightward movement of the piston 27 to effect thereby, throughthe disclosed linkage, leftward extension of the auxiliary movablecontact 16. As a result, all arcing will take place between the movablecontact 13 and the pressureresponsive auxiliary movable arcing contact16. As mentioned hereinbefore, the arc-resisting tip 16a insuresresistance to arc-erosive action.

The practice used for switch connection in the high voltage compartmentof the compressed-air circuit breakers incorporates the technique of amoving contact arm fitting between finger contacts, which gives goodcontacting pressure in the closed position. During are interruption, thearc is drawn upon the finger contacts and moved upwardly from thecontact fingers to an arc tip directly above them due to the magneticeffect of the looped current path through the breaker plus the action ofthe compressed-air blast. A silver-tungsten tip embedded in the uppercontact finger is electrically a part of the upper terminal casting.This tip is highly arc-resistant and withstands the burning action ofthe are thus eliminating burning of the contact fingers.

The circuit interrupter used for electric arc furnace duty is subjectedto a larger number of operations than those used for power-house serviceduty thus increasing the mechanical wear on the moving parts. Thisincreased mechanical wear on the moving contact arm and finger contacts,due to the two sliding metal-to-metal surfaces, causes grooves to formupon the cupaloy surfaces and results in extensive burning of the fingercontacts. This may result in the frequent replacement of parts.

In the present invention, it is proposed to use a combination ofpneumatically-operated butt and finger contacts. Thepneumatically-operated butt contacts 16, with a silver-tungsten tip 16a,will reduce the mechanical wear exerted upon the arcing surfaces and canbe adjusted to extend well beyond the finger contacts thus eliminatingburning of the finger contacts 14a. During arc interruption, the arcwill be drawn upon the silver-tungsten surface 16a of the butt contact16, which will withstand the burning action of the arc. The fingercontacts will give good contacting pressure for carrying normal loadcurrent of the interrupter.

As illustrated in FIG. 2, the physical structure of the contactarrangement comprises a piston 27 mounted within an operating cylinder32 and connected by a mechanical lever 21 to the butt contact 16, whichis operated by the air pressure during arc interruption and is returnedby the stored energy in a compression spring 33 following areinterruption.

The opening operation is as follows: During arc interruption, rotationof the shaft cam causes various levers to open a blast valve, thusallowing compressed air to pass from the reservoir tank 2 upwardlythrough the blast tube 5 and between the separating contacts 13, 14.Compressed air at the same time travels through a pipe connection 28,connected with the blast tube 5, and puts air pressure upon the piston27 mounted in the aluminum cylinder 32. The piston 27 is connected bythe mechanical lever 21 to the butt contact 16. R0- tatable lever 21 ispivotally mounted at the fixed pivot 22 by a brace 34 to give thedesired forward and backward movement of the contact 16 during and afterarc interruption. The force exerted upon the piston 27 is such that upontripping of the breaker the acceleration of the butt contact 16 will begreat enough to prevent the moving contact arm 13 from running away fromthe butt contact 16, thus eliminating arcing upon the contact fingers14a, The silver-tungsten tip 16a embedded in the butt contact 16withstands the burning action exerted by the arc. FIG. 3 shows theposition of the contacts 13, 14 with the movable arcing contact 16extended.

During arc interruption, spring 33 is compressed, and the stored energyused for subsequent returning of piston 27 to the closed-position uponcompletion of the interruption. After circuit interruption, the shaftcam 10 allows the blast-valve levers to drop off the cam, and the blastvalve recloses. This exhausts the compressed air within blast tube 5 toatmosphere, which at the same time exhausts the air within conduit 28and in back of piston 27, thus allowing compression spring 33 to returnthe piston 27 to the closed position.

FIGS. 4-6 illustrate a modification of the invention, as applied to thesame type of compressed-gas circuit interrupter, as illustrated inFIG, 1. A trifurcated hookshaped movable contact arm 40 cooperates withthree spaced jaw-type relatively stationary contacts 41-43 to completethe electrical circuit passing through the interrupter, as illustratedin the closed-circuit position of the interrupter 1, as exemplified inFIGS. 4 and 5 of the drawings. As more fully disclosed in FIG. 5, thetrifurcated movable contact 40 includes an outer pair of main movablecontacts 40a, 40c. Interposed between the outer main contacts 40a, 40cis an intermediate movable arcing contact 40b. It will be observed thatthe intervening movable arcing contact 4012 is disposed directly abovethe exhaust end 45 of the blast tube 5 so as to receive a direct blastof gas therefrom.

Relatively stationary main contacts 41, 43 have pistons 47 securedthereto, which are operable within pistonoperating cylinders 48. Asviewed in FIG. 4, an air inlet passage 28' pneumatically interconnectsthe interior 31 of the blast tube 5 with the working faces 47a of thepistons 47 so as to exert fluid pressure thereon in a direction to drivethe pistons 47 and hence the relatively stationary main contacts 41, 43,in a rightward opening direction to thereby more quickly effect theseparation thereof from the movable main contacts 40a, 40c.

Preferably retracting springs 49 are provided, disposed between the baseportions 41a, 43a of the relatively stationary main contacts 41, 43respectively, and the cylinder heads 48, so as to effect retraction ofthe main stationary contacts 41, 43 following cessation of the gas blasttraversing the blast tube 5.

In a manner similar to that previously described in connection withFIGS. 1-3 of the drawings, during the opening operation blast pressurecauses rightward movement of the movable stationary main contacts 41, 43from the movable main contacts 40a, 4110 to quickly effect separationtherefrom. During the counterclock- Wise rotative opening movement ofthe trifurcated movable contact 40 about the pivot 50, as caused by theoperating rod 51, an arc is established over the exhaust end 45 of theblast tube 5, whereby the upwardly passing flow of high-pressure gascarries the established are upwardly into the arc-chute structure 6,where arc extinction occurs in a manner described by the aforesaidpatent.

FIG. 6 illustrates fragmentarily the position of the several partsduring the opening operation, when the relatively stationary maincontacts 41, 43 have been retracted by the operation of the gas blast.Following closing of the blast-valve structure 4, anda reduction ofpressure within the blast tube 5, the retracting spring 49 effectsleftward movement of the relatively stationary main contacts 41, 43 tothe position illustrated in FIGS. 4 and 5 of the drawings.

The practice used for high continuous current rated low-voltagecompressed-air circuit breakers incorporates the combination of main andarcing contacts. The main contacts are used for carrying the currentrating of the breaker, and the arcing contacts are those on which thearc is drawn after the main contacts have separated. In order to preventarcing upon the main contacts, the

moving mains are adjusted for a inch overlap on the finger contacts anda 2 /8 inch overlap of the moving arcing contact. This excessive overlapof the moving arcing armincreases the tripping time of the breaker. Asdefined. herein, the tripping time is the interval existing between theenergizing of .the trip coil and the parting of the arcing contacts.

In the present invention it is proposed to use pneu matically-operatedmain finger contacts, which, during arc interruption, will part from themoving main contacts before starting movement of the moving contacts.This will decrease the amount of overlap needed on the arcing contact,thereby decreasing the tripping time of the breaker.

The physical structure of the pneumatically-actuated contact structurecomprises a pneumatically operated piston 47 mechanically connected toeach relatively main finger contact 41, 43 and operated by air pressureduring arc interruption, and returned by the stored energy in the spring49 after circuit interruption.

By way of recapitulation, the sequence of operation is such that duringarc interruption, the trip coil of the magnet valve is energizedallowing compressed air from the breaker reservoir tank 2 to passthrough the valve on the upper side of the pneumatic mechanism, whichoperates the shaft 7 for parting of the moving contact arms 40.Compressed air at the same time will travel through blast pipeconnection 5 on the outlet side of the blast valve within valve casing12 to the back of contact pistons 47. This compressed air is thenutilized to operate the contact pistons 47, breaking the contact betweenthe relatively stationary main contacts 41, 43 and the outer contacts40a, 40c of the trifurcated movable contact 40 before movement of thearcing contact 40b. This is accomplished due to the amount of overtoggleof the shaft 7 with respect to the operating rod 51 that locks thebreaker in the closed position.

After circuit interruption, the compressed air is exhausted in back ofthe pistons 47 due to the reduction in air pressure in the upper part ofthe blast tube 5 and conduit 28' after blast-valve reclosure allowingthereby the stored energy in the springs 49 to return the contactpistons 47 to their closed positions, as illustrated in FIGS. 4 and 5 ofthe drawings.

The arrangement illustrated in FIG. 2 of the drawings utilizing theavailable air blast provides positive follow of the arcing contactsduring interruption of the circuit, yet does not allow the usualrestricting force of biasing springs which oppose closing of the circuitbreaker. Thus the full closing effort of the mechanism is available forovercoming magnetic forces and permits using a smaller mechanism onhigher-rated breakers.

Although there has been illustrated and described specific structures,it is to be clearly understood that the same were merely for the purposeof illustration, and that changes and modifications may readily be madetherein by those skilled in the art, without departing from the spiritand scope of the invention.

We claim as our invention:

1. A compressed-gas circuit interrupter having a tank of compressed gas,a blast tube, an arc chute at the upper end of said blast tube, atrifurcated hook-shaped movable contact cooperable with threeside-by-side relatively stationary jaw-type contacts to complete theelectrical circuit through the interrupter, the central stationaryjawtype contact being immovable, the combination therewith of pistonsassociated with the outer relatively stationary contacts, conduit meansinterconnecting said pistons with the blast tube, whereby the outerrelatively stationary contacts move in an opposite direction than themovable trifurcated contact to increase the speed of arc drawal, andfurther whereby said central stationary jaw-type contact acts as astationary arcing contact.

2. A compressed-gas type of circuit interrupter including a pair ofside-by-side relatively stationary contacts,

, and the other relatively fixed in relation thereto, a pair ofcooperating simultaneously movable contacts movable in the samedirection and cooperable with said pair of sideby-side relativelystationary contacts, a source of highpressure gas, conduit means forsupplying a blast of highpressure gas to the space between said otherrelatively stationary contact and one of the movable contacts forarc-extinguishing purposes, means utilizing a portion of thehigh-pressure gas flowing through said conduit means to pneumaticallymove said one relatively stationary contact in a direction opposite tothe opening direction of the movable contacts, whereby arcing will occuronly between said other relatively stationary contact and said onemovable contact.

3. The combination in a gas-blast type of circuit interrupter of asource of gas under pressure, a pair of separable main contacts, amovable auxiliary arcing contact, means electrically connecting themovable auxiliary arcing contact with one of said separable maincontacts, pneumatic means responsive only to the opening operation ofthe interrupter to move said movable auxiliary contact in the openingdirection of movement of the other of said separable main contacts,whereby said one main contact may be relieved from arcing, and biasingmeans em ployed for efiecting retraction of said movable auxiliaryarcing contact to thereby minimize the closing eflort imposed upon anassociated operating mechanism.

4. A gas-blast type of circuit interrupter including a relativelystationary jaw-type contact, a movable bladeshaped contact cooperablewith said relatively stationary jaw-type contact to complete theelectrical circuit through the interrupter, a movable auxiliary arcingcontact, means electrically connecting the movable auxiliary arcingcontact to said relatively stationary jaw-type contact, pneumatic meansresponsive only to the opening operation of the interrupter to move saidmovable auxiliary arcing contact in the opening direction of movement ofsaid bladeshaped contact, whereby said relatively stationary jawtypecontact may be relieved from arcing, and biasing means employed toeifect retraction of the movable auxiliary arcing contact to therebyminimize the closing efiort imposed upon an associated operatingmechanism.

5. A gas-blast type of circuit interrupter including a relativelystationary jaw-type contact, a movable bladeshaped contact cooperablewith said relatively stationary aw-type contact to complete theelectrical circuit through the interrupter, a movable auxiliary arcingcontact, means electrically connecting the movable auxiliary arcingcontact to said relatively stationary jaw-type contact, a tank of gasunder pressure, a blast tube for communicating said tank with the regionadjacent said contacts for are interruption, blast-valve means forcontrolling the flow of high pressure gas through said blast tube,pneumatic means responsive only to the opening operation of theinterrupter to move said movable auxiliary arcing contact in the openingdirection of movement of said blade-shaped contact, whereby saidrelatively stationary jaw-type contact may be relieved from arcing, andbiasing means employed for etfecting retraction of the movable auxiliaryarcing contact to thereby minimize the closing eflfort imposed upon anassociated operating mechanism.

6. A circuit interrupter including a pair of separable main contacts,means defining a pair of separable arcing contacts, means responsiveonly to the opening operation of the interrupter to effect simultaneousopposite opening movement of said pair of separable main contacts,whereby arc drawal upon the pair of separable arcing contacts may bemore rapidly achieved, and spring retraction means employed inconnection with at least one of the separable main contacts toreposition the same at the end of the opening operation to a point whichis closer to the cooperating movable main contact than the position ofthe same during the opening movement thereof.

7. A circuit interrupter including a pair of separable main contacts,means defining a pair of separable arcing contacts, means mechanicallyand electrically interconnecting one of said main and arcing contacts,means responsive only to the opening operation of the interrupter toeffect simultaneous opposite opening movement of said pair of separablemain contacts, whereby arc drawa'l upon the pair of separable arcingcontacts may be more rapidly achieved, and spring-biased retractionmeans associated with one of the pair of separable main contacts.

8. In combination, a pair of separable main contacts, means defining apair of separable arcing contacts, a source of gas under pressure, ablast tube for transmitting a flow of high pressure gas from said sourceto the region adjacent said contacts, means responsive only .to theopeningoperation of the interrupter to effect simultaneous oppositeopening movement-of said pair of separable main contacts, whereby arcdrawal upon the pair of separable arcing contacts may be more rapidlyachieved, and the responsive means including a pressure operated piston,and spring-biased retraction means associated with said piston.

References Cited by the Examiner UNITED STATES PATENTS 1,834,550 12/31Reed 200--151 1,910,714 5/33 Reed 200 -151 1,944,403 1/3'4 Clerc '2001482,822,449 2/58 Thommen 200-146 FOREIGN PATENTS 448,558 5/48 Canada.643,304 4/ 37 Germany. 675,370 5/ 39 Germany. 87,834 11/36 .Sweden.97,040 '10/ 39 Sweden.

KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD ,A. GILHEANY, Examiner.

1. A COMPRESSED-GAS CIRCUIT INTERUPTER HAVING A TANK OF COMPRESSED GAS,A BLAST TUBE, AN ARC CHUTE AT THE UPPER END OF SAID BLAST TUBE, ATRIFURCATED HOOK-SHAPED MOVABLE CONTACT COOPERABLE WITH THREESIDE-BY-SIDE RELATIVELY STATIONARY JAW-TYPE CONTACTS TO COMPLETE THEELECTRICAL CIRCUIT THROUGH THE INTERRUPTER, THE CENTRAL STATIONARYJAWTYPE CONTACT BEING IMMOVABLE, THE COMBINATION THEREWITH OF PISTONSASSOCIATED WITH THE OUTER RELATIVELY STATIONARY CONTACTS, CONDUIT MEANSINTERCONNECTING SAID PISTONS WITH THE BLAST TUBE, WHEREBY THE OUTERRELATIVELY STATIONARY CONTACTS MOVE IN AN OPPOSITE DIRECTION THAN THEMOVABLE TRIFURCATED CONTACT TO INCREASE THE SPEED OF ARC DRAWAL, AND